I had purchased one on eBay claimed as a new cable but the cable was defective. The Dragoncast cable has a high % of not working. Its most frustrating to have all the goods arranged and set up ready to play doubles of everything then to find out the cable is defective.

If you find one on eBay or from any seller it would be great to do as you are, ask and make sure it works before hand or ask for return policies.